1. Field of the Invention
The present invention relates to a digital camera, and more particularly to a digital camera which is provided with an optical zoom function and an electronic zoom function.
2. Description of the Related Art
In recent years, digital cameras, such as digital still cameras, digital video cameras and the like, that are provided with both an optical zoom function and an electronic zoom function have become widespread.
Conventionally, in such a digital camera, from the viewpoint of maintaining quality of images obtained by photography (subject images), zooming has been implemented by the optical zoom function in a range of photographic magnification corresponding to the optical zoom function, and zooming with the electronic zoom function has been implemented in cases in which zooming beyond that range was to be implemented. Note that, although an electronic zoom function may also be referred to as a digital zoom function, the term “electronic zoom function” is used throughout the present specification.
Now, when zooming is to be implemented by an optical zoom function, it is necessary to move a lens that is provided at the digital camera in an optical axis direction and change a focusing distance which depends on that lens. Ordinarily, a motor such as a stepper motor or the like (below referred to as a “zoom motor”) is employed as moving means therefor (see Japanese Patent Application Laid-Open (JP-A) Nos. 2000-224455, 2001-211373 and the like).
Consequently, there has been a problem with this kind of digital camera, in that the zoom motor is driven when zooming is to be implemented within a range of photographic magnification corresponding to the optical zoom function, and therefore power consumption is high.
As a result, when the power consumption during zooming is large, there is a problem in that, assuming that the digital camera is being used in a mobile environment, because of the effect of the electric power being drawn by the zoom motor in a digital camera that employs a battery as a power source, a number of photographic images that can be captured is decreased. Further problems and the like may arise, such as, in a digital camera which is capable of executing multi-tasking of various internal processes for the purpose of increasing the speed of photography, it being necessary in some cases to apply a limit to the internal processes that can be concurrently implemented because of the effect of the electric power that is drawn by the zoom motor.
Accordingly, in order to solve the above-described problems with the power consumption being large during zooming, JP-A No. 2000-111785 has proposed a technique of reducing power consumption during zooming of a zoom mechanism of a lens by, at a point in time before photography, monitor-displaying a subject image for which electronic zoom processing has been carried out in accordance with a focusing distance specified by a zoom button, without operating the zoom mechanism of the lens, and using the zoom mechanism to set the lens to the focusing distance that has been specified only at a time of photography.
In the technique described in JP-A No. 2000-111785, the power consumption during zooming can be reduced. However, because the zoom mechanism is operated only during photography, although there is no problem if a difference between the photographic magnification that was set before by electronic zoom processing before photography and the photographic magnification of the optical zoom that was set at the time of photography is small, in a case in which this difference is large, for example, a case in which the photographic magnification set by the electronic zoom processing is a minimum photographic magnification and the photographic magnification of the optical zoom that was set at the time of photography is a maximum photographic magnification or the like, there is a problem in that a time difference between a time of instructing photography by pressing-operation of a release button (a “shutter”) and a time of actual photography becomes large. In cases in which this time difference is large, operational feedback during photography will seem incongruous to a photographer, in addition to which good “shutter chance” moments may be missed, and these are serious problems.